Gas-operated self-loading firearm



April 18, 1944. D. M wlLLlAMS 2,346,954

GAS-OPERATED SELF-LOADING FIREARM Filed Oct. 26, 1940 3 Sheets-Sheet l n nl?" mi Aprll 18, 1944. D. M. wxLLlAMs GAS-OPERATED SELF-LOADING FIREARM Filed Oct. 26, 1940 3 Sheets-Sheet 2 GAS-OPERATED SELF-LOADING FIREARM Patented Apr. 18, 1944 GAS-OPERATED SELF-LOADING FIREARM David M. Williams, New Haven, Conn.,assignor to Western Cartridge Company, New Haven, Conn., a corporation of Delaware Application October 26, 1940, Serial No. 362,943 In Canada October 7, 1940 7 Claims. (Cl- 42-3) The present invention relates to improvements in gas-operated self-loading firearms, that is to say, firearms of the type wherein gas pressure developed by the discharge of a cartridge is caused to impinge against a piston or its equivalent which in turn effects the retraction of the breech-bolt and the extraction and ejection of the just-red cartridge preparatory to the automatic insertion of a fresh cartridge when the said breech-bolt returns into its breech-closing position.

One of the objects of the present invention is to provide a superior gas-operated self-loading firearm having a superior construction and arrangement of parts whereby the firearm is capable of long periods of use without occasioning the breakage, derangement or clogging of the parts.

Another object of the present invention is to provide a superior self-loading firearm of the type referred to wherein the relatively-long-distance retirement of the breech-bolt may be reliably effected by means of a gas-operated piston having a total stroke of but a fractional part of the stroke of the said breech-bolt.

A further object of the present invention is to provide a superior gas-operated self-loading rearm characterized by fewness of parts and relative lightness combined with strength and ruggedness.

A still further object of the present invention is to provide a superior rearm of the character referred to and having a superior gas-operated piston and associated cylinder, and wherein the fouling of the piston and cylinder is so minimized as to be negligible.

Still another object of the present invention is to provide a superior gas-operated self-loading firearm having a gas-operated piston and associated cylinder constructed and arranged so that theexcessively hot gases acting upon the same do not materially erode either the piston, the cylinder structure or the passages leading to the latter.

Another object of the present invention is to provide a rearm of Ithe character referred to, with a superior piston and associated cylinder so constructed and arranged that the said piston will discharge its full function without harmfully lowering the gas pressure in the barrel of the firearm.

A further object of the present invention is to provide a superior gas-operated self-loading iirearm wherein the gas pressure initially effective in moving the breech-bolt rearwardly, is automatically limited so as to permit the said breechbolt to coast into its retired position and to have its rearward movement checked independently of the said piston without requiring that the checking mechanism also function to check the piston and the gas pressure applied thereto.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes al1 features in the said disclosure which are novel over the prior art and which are not claimed in anil separate application.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a broken view partly in side elevation and partly in vertical central-longitudinal section of a gas-operated self-loading iirearm embodying the present invention, the parts being shown in the positions which they assume when the breech-bolt is in its breech-closing position; g

Fig. 2 is a view similar to Fig. 1 but showing the parts in the positions which they assume when the breech-bolt is moved into its fullyretired position as a result of the discharge of the firearm;

Fig. 3 is a broken view partly in side elevation and mainly in vertical central-longitudinal section of the portion of the firearm immediately adjacent the gas-operated' piston thereof together with a fragment of the action-slide;

Fig. 4 is a transverse sectional View taken on the line 4--4 of Fig. 3;

Fig. 5 is a similar view taken on the line 5-5 of Fig. 3;

Fig. 6 is a broken perspective view partly in section of the portion of the barrel immediately adjacent the cylinder-lug thereof;

Fig. 7 is a detached perspective view of the piston;

Fig. 8 is a detached perspective view of the tubular stop-member;

Fig. 9 is a view in rear elevation o the breechbolt detached, together with the bolt-operating link;

Fig. 10 is a view thereof in side elevation;

Fig. 11 is a top or plan view of the action-slide, detached; and

Fig. 12 is a view thereof in central verticallongitudinal section.

The particular gas-operated self-loading rearm herein chosen for the purpose of illustrating the present invention includes a barrel 20 rigidly attached at its rear to the forward end of a receiver 2|, and having the usual axial bore 22 extending longitudinally therethrough and through which bore bullets are forwardly propelled in the usual manner of firearms. Attached to the barrel 20 and the receiver 2| is a stock generally designated by the reference character 23.

The stock 23 is preferably formed of wood or other heat-insulating and shock-absorbing material and includes a buttstock-portion 24 and a forestock-portion 25. The said buttstock-portion 24 nes mainly to the rear of the receiver 2| while the said forestock-portion 25 lies mainly forwardly of the said receiver. The upper face of the forestock-portion 25 is formed with an upwardly-opening longitudinal groove 26 receiving the lower portion of the barrel 20 and also certain other features of the rearm as will be hereinafter described. At about the junction point between its buttstock-portion 24 and its forestock-portion 25 the stock 23 is formed with a vertical-longitudinal passage 21 which opens downwardly through the under face of the stock 23 and which connects the said under face with an upwardly-opening recess 23 which latter accommodates the receiver 2| and other features of the rearm and also communicates at its forward end with the longitudinal groove 26 in the forestock-portion 25.

At a point forwardly of the receiver 2| the barrel 20 is-provided with an integral depending cylinder-lug 29 having a rearwardly-opening cylindrically-contoured piston-chamber 30 therein, provided with a relatively-heavy front wall 3|. The said piston-chamber 30, while substantially horizontal, slopes downwardly and rearwardly in parallelism with a reciprocating actionslide generally designated by the reference character 32 and described hereinafter in more detail.

The forward portion of the piston-chamber 30 in the cylinder-lug 29 is of smooth cylindrical form while the rear portion thereof is internally threaded as is particularly we'll shown in Figs. 3 and 6. Installed in the rear portion of the pistonchamber 30 is an externally-threaded tubular stop-member 33 having an axial passage 34 extending therethrough from front to rear as is particularly well shown in Figs. 3 and 8. The said axial passage 34 receives with a sliding llt the cylindrically-contoured stem 35 of a piston generally designated by the reference character 36. The said piston 36, in addition to its rearwardly-extending stem 25, includes at its forward end a rigid cylindricaily-contoured head 31 having a sliding iit in the smooth cylindrical forward portion of the piston-chamber 30 before referred to.

At the junction point of its stem 35 and its head 31 the piston 36 is formed with a rearwardly-facing conically-contoured annular sealing-surface 38 which is adapted to engage with the similarly-contoured but forwardly-facing sealing-seat 39 formed in the forward portion of the tubular stop-member 33 around the forward terminus of the axial passage 34 therein.

Leading forwardly and upwardly from the forward portion of the piston-chamber 30 in the cylinder-lug 29 is a gas-passage 40 communicating at its upper end with the bore 22 in the barrel 20 as is especially well shown in Fig. 6. The lower end of the said gas-passage 40 intersects the rear face of the front wall 3| of the cylinder-lug 29 at a point slightly below the upper end thereof so that'the front face of the head 31 of the piston 36 normally covers the same. 'I'he drilling of the gas-passage 40 in the particular position shown is made conven- 43-43 each of which receives with a slidingfit the adjacent one of two laterally-spaced-apart guide-fingers 44-44 extending forwardly fromy each of the respective opposite sides of the actionslide 32 before referred to. The said guidengers 44-44 constitute in effect integral for# ward continuations of a front crosshead 45 formed integral with and located adjacent the forward end of the action-slide 32. The said crosshead 45 has its forward face normally in engagement with the rear face of the projecting stem 35 of the piston 36.

Formed integral with and extending rearward: ly from the respective opposite sides of the real: portion of the front crosshead 45 are two iat-l erally-spaced-apart side-bars 45--46 which in turn merge at their rear ends in an integral rear crosshead 41 of the said action-slide. The forward portion of the said rear crosshead 41 is provided with a forwardly-opening notch 45,; as is especially well shown in Figs. 11 and l2, to receive the normally-lower end of a bolt-operating link 49 pivoted to the said crosshead by means of a pivot-pin 50 extending transversely` through the said crosshead and through the lowerv end of the said link 49.

The rear crosshead 41 of the action-slide 32 is also formed with a rigid rearwardly-extending cylindrically-contoured stem 5| extendable freely rearwardly throu-gh a passage 52 formed in an' integral arm 53 depending from the rear end of the receiver 2|. The said stem 5| is also extendable rearwardly through a passage 54 formed in a coupling-shoe 55 mounted in the' rear end of the rear portion of the upwardlyopening recess 28 in the stock 23 as is shown in Fig. 1. The rear face of the stem 5| of the action-slide 32 has thrusting forwardly against it a follower 56 reciprocating in a spring-housing tube 51 extending rearwardly from and rigidly attached at its forward end to the said couplingshoe 55. The said spring-housing tube houses a helical breech-closing spring 59 which thrustsv forwardly against the follower 59 and acting' through the said follower yieldingly urges the` action-slide 32 into its foremost position as shown in Fig. 1.

Returning now to the bolt-operating link 4l it will be noted that the same is connected by means of a pivot-pin 59 at its normally-upper end to the rear end of a breech-bolt 69 movable in the receiver 2l. The said breech-bolt 50 is formed at its upper rear corner with a rearwardly-facing locking-abutment 5| engageable with a forwardly-facing locking-abutment 52 formed in the receiver 2|.

'I'he action-slide 32 has the upper faces or edges of its complemental side-bars 45-43 normally bearing against the under surfaces of the adjacent portions of the receiver 2|. The under faces or edges of the side-bars 45-45 bear against the adjacent upper surfaces of a triggerplate unit 53 (Figs. 1 and 2) which latter il accommodated mainly in the vertical-longitudinal passage 21 in the stock 23 and may be attached to the receiver 2l in any suitable manner and have the characteristics such, for instance, as is illustrated in my co-pending Patent No. 2,289,158 led on even date herewith.

To provide for the manual retraction of the action-slide 32 and hence also the breech-bolt 66, a manual operating-slide 64 is employed as is shown in Figs. 1 and 2. The said operating-slide is pivoted at its forward end by means of a coupling-pin 65 to the front crosshead 45 of the said action-slide 32. The rear end of the operating-slide 64 is provided with a laterallyprojecting operating-handle 66 and is guided for reciprocation in a guide-groove 61 formed in the right side-wall of the receiver 2|.

Cartridges may be fed to the firearm in any approved manner such, for instance, as by means of a box magazine common in military firearms. The rearm may be discharged by any suitable ring mechanism not requiring detailed illustration or description herein and which firing mechanism is controlled by a trigger 68 projecting into the space defined by a loop-like triggerguard 69 formed integral with and depending from the trigger-plate unit 63 before referred to.

In a manner as will more fully hereinafter appear, the rearward movement of the action-slide 32 is checked by the engagement of the rear face of its front crosshead 45 with the forward face of an abutment-lug 10. 'I'he said abutmentlug rigidly depends from and is preferably formed integral with the forward portion of the receiver 2l.

Operation For the purpose of making clear the functioning of the gas-operated self-loading firearm above described and shown in the accompanying drawings, it may be assumed that the firearm is loaded, the breech-bolt 60 is in its breechclosing position as shown in Fig. 1, and that the firearm is cocked.

The firearm may now be discharged by pulling rearwardly upon the trigger 68 with theresult that a bullet will be forced forwardly through the bore 22 of the barrel 20. The resultant gas pressure from the discharge of the just-red cartridge will pass downwardly and rearwardly in an inclined path from the bore 22 of the barrel 20 through the inclined gas-passage 40 and will rst impinge upon only that relativelysmall area of the forward face of the head 31 of the piston 36`4 which now covers the lower end of the said gas-passage. The said piston will be forced sharply rearwardly by the gas pressure and will then have the entire area of the front face of its head 31 acted upon by the gas and the movement of the piston will continue until its annular sealing-surface 38 engages with the annular sealing-seat 39 at the forward end of the tubular stop-member 33. By the engagement just referred to the rearward movement of the piston v36 will be checked and the escape of gases rearwardly from the piston-chamber 30 will be prevented.

The very rapid and relatively-short rearward travel of the piston 30 under the urge of the gases as above described, will impart to the action-slide 32 a similar movement rearwardly of the firearm structure, which movement, however, will continue after the said piston has ceased its rapid but short rearward movement.

until the parts reach the positions in which they are shown in Fig. 2.

Immediately following the start of the rearward movement of the action-slide 32 as above described, the lower end -of the bolt-operating link 49 will be moved rearwardly and thus first pull mainly downwardly upon the rear end of the breech-bolt 60. The downward movement of the rear end of the breech-bolt 60, as just referred to, will disengage the locking-abutment 6| thereof from the locking-abutment-62 in the receiver 2l.

When the rear end of the breech-bolt 60 has been rocked downwardly to unlock the same as above described, the continued rearward movement of the action-slide 32 as the same coasts rearwardly under the impulse imparted to it by the piston 36, will, through the intermediary of the bolt-operating link 49, pull rearwardly upon the said breech-bolt until the parts assume the positions in which they are shown in Fig. 2. The rearward movement of the action-slide and hence also of the breech-bolt 60 and associated parts will be checked by the engagement of the rear face of the front crosshead 45 of the said actionslide with the front face of the abutment-lug 10 rigidly depending from the forward portion of the receiver 2|.

The above-described rearward movement of the action-slide 32, breech-bolt 60 and associated parts, will be accomplished against the counterurge of the helical breech-closing spring 58 as the stem 5I of the action-slide 32 moves rearwardly through the passage 52 in the rear end of the receiver 2| and through the passage 54 in the coupling-shoe 55.

The retirement of the breech-bolt into its fullyretired position as above described and as is especially well shown in Fig. 2, will, in the normal manner of self-loading firearms, eiect the extraction and ejection of the case of the justred cartridge.

Immediately following the reaching by the breech-bolt 60 and the action-slide 32 of their' rearmost positions, the breech-closing spring 58 will assert itself to move the said action-slide forwardly into its normal position as shown in Fig. 1. The movement just referred to will cause the front face of the front crosshead 45 of the action-slide to re-engage with the rear face of the stem 35 ofthe piston 36, thus causing the said piston to move forwardly until the forward face of its head 31 is again seated against the rear face of the front wall 3| of the pistonchamber 30.

The forward movement of the action-slide 32 as above described, will act through the boltoperating link 49 to move the breech-bolt 60 forwardly, and when the locking-abutment 6| of the said breech-bolt has been brought 'into registration with the locking-abutment 62 of the receiver 2|, the rear end of the said breech-boit will be lifted upwardly to re-engage the 'two said locking-abutments and the said breech-bolt will be thereby locked in its full breech-closing position as shown in Fig. l.

During. the forward movement of the breechbolt as above described, a fresh cartridge will, in a manner well known in the art, be installed in the cartridge-chamber of the firearm preparatory to the latter again being discharged, and the cycle of operation above described repeated.

Advantages By providing a gas-actuated piston which at the termination of its power stroke is sealed against the escape of hot gases around it, the very serious and common erosion or "wire-drawing effects are substantially eliminated, whereas were the said hot gases to be permitted to escape past the piston the life of the same and also the life of the cylinder structure in which it moves and the gas-passage would be relatively short and the functioning of the firearm rendered nonuniform and uncertain.

Another advantage of the present structure which may be mentioned resides in the fact that the action-slide 32 or its equivalent, instead of having its rearward travel checked by Ysome abutment adjacent the rear end of the said actionslide, is checked adjacent its forward end by the engagement of its front crosshead 45 with the abutment-lug 'I0 of the receiver 2|. Under these conditions the side-bars 46-46 of the actionslide 32 may be relatively slender and therefore appreciably lighter inasmuch as they are not subjected to the excessive compressive strain of checking the rearward movement of the said action-slide, breech-bolt and associated parts.

By providing the cylinder structure with an inclined gas-passage such as the gas-passage 40, which aligns with a clearance-notch such as the clearance-notch 4|, not only may the said passage be readily drilled; and cleaned but the tubular stop-member 33 or its equivalent may serve to cover the said clearance-notch when the` parts are assembled.

A further advantage of having a structure in which the gas-operated piston coacts with the cylinder structure to seal against the escape of hot gases and by limiting the stroke of the said piston to a fractional part of the stroke required of the breech-bolt 60 or its equivalent, resides in the fact that the very rapid fall-oil in gas pressure in the bore 22 of the barrel 20 is avoided and the maximum muzzle velocity of the projectile is assured.

By downwardly and rearwardly inclining .the piston-chamber or its equivalent to conform to the downward and rearward inclination of the path of movement of the action-slide 32, lateral strains upon the structure are so minimized as not to constitute a serious problem.

Another advantage of the present structure to which attention may be called, resides in the fact that when the piston 36 or its equivalent is at its normal position as shown particularly well in Fig. 3, it has but a fractional portion of the total area of its forward face exposed to the initial impact of the hot gases since the normal impingement of the front face of the said piston against the rear face of the front wall 3l of the cylinder-lug 2S, leaves exposed to the initial impact of the gases only an area corresponding to the area of the lower end of the gas-passage 40.

While I do not claim that the coupling of a breech-bolt to an action-slide by means of a boltoperating link such as 49 is new per se, I have found that the said construction when combined with a short-stroke piston produces novel and highly-advantageous results. 'I'his point will be appreciated when it is realized that it is highly desirable to maintain the forward face of the crosshead 45 of the action-slide 32 or its equivalent normally pressed against the rear end of the short-stroke piston 36 when the breech-bolt is in its full breech-closing position. I have found that by means of the bolt-operating link or its equivalent the desired contact may be maintained wide tolerances ln manufacture while at the same time insuring that the breech-bolt will be securely held in its locked breech-closing position. By reference to the drawings it will be seen that the action-slide 32 may be located either slightly to the rear or slightly forwardly of the position in which it is shown in Fig. 1 without affecting the secure locking of the breech-bolt l0. Thus, despite wear. expansion, contraction and' other variables, the action-slide 32 may be maintained in engagement with the piston 38 in readiness for receiving a rearward impulse therefrom when the firearm is discharged, while, at the same time. the secure locking 0f the breech-bolt I3 is not materially affected by the variations in position referred to.

'I'he task of checking the rearward movement of the action-slide 32, breech-bolt and associated parts is rendered much easier with a construction like that exemplied in the accompanying drawings inasmuch as the major portion of the travel of the said parts in a rearward direction is a coasting action and the dynamic rearward drive of the piston has long ceased before the said action-slide,'breechbolt, etc., require checking. In other words, the means employed for checking the rearward movement of the actionslide, breech-bolt and associated parts, does not also have the burden of effecting such checking while the said parts are under the active driving urge of the piston. The piston itself is being checked after a. relatively-short travel by the tubular stop-member 33.

Other advantages will be apparent to those skilled in the art from the foregoing description considered in conjunction with the accompanying drawings.

The invention maybe carried. out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A gas-operated self-loading firearm including in combination: a receiver; a barrel extending forwardly from the said receiver and having a rigid cylinder-lug depending therefrom and provided with a rearwardly-opening pistonchamber and with a gas-passage connecting the forward end thereof with the bore of the said barrel, the said cylinder-lug being provided on each of its respective opposite sides with one of two outwardly-opening longitudinal guidegrooves; a piston in the piston-chamber of the said cylinder-lug; an action-slide operatively associated with the said piston for actuation thereby and mounted for reciprocation beneath both the said barrel and the said receiver and having longitudinal guiding-DQrtions jointly embracing the respective opposite sides of the cylinder-lug of the said barrel and respectively sliding in one of the guide-grooves therein; a breech-bolt reciprocating in the said receiver; and means operatively connecting a rear-portion of the said action-slide with the said breech-bolt.

2. A gas-operated -self-loading firearm-construction including in combination: a barrel having an axial bore; a cylinder adjacent the said barrel and provided with a rearwardly-opening under varying conditions and with relatively- 7| piston-chamber and with a gas-passage connecting the iorward portion of the said piston-chamber with the bore of the said barrel, the said cylinder being formed in the rear of said pistonchamber thereof with internal threads; a tubular bushing having an axial passage smaller in diameter than the diameter of the piston-chamber oi the said cylinder and formed externally with screw-threads interiitting with the screw-threads in the piston-chamber of the said cylinder, the said bushing being provided with an annular forwardly-facing sealing-seat; and a piston comprising a head slidable in the piston-chamber of the said cylinder and also comprising a cylindrically-contoured stem of lesser` diameter than the said head and slidably extending through the axial passage in the said bushing, the said piston also including an annular rearwardly-facing sealmg-suriace engaging with the annular sealingseat of the said bushing when the said piston is moved rearwardly by gas pressure in the said piston-chamber.

3. A gas-operated self-loading iirearm-construction as set forth in claim 2, and in which the annular forwardly-facing sealing-seat of the said bushing is conically contoured and in which the annular rearwardly-facing sealing-surface of the said piston is oonically contoured for ensagement with the similarly contoured sealingseat of the said bushing.

4. A gas-operated self-loading firearm-construction including in combination: a barrel having an axial bore; a cylinder adjacent the said barrel and provided with a piston-chamber open at one end, the said cylinder being also formed with a gas-passage connecting the bore of the said barrel and the piston-chamber of the said cylinder, the said cylinder being also formed in a wall remote from the said barrel with a drillclearance passage adjacent the open end of the piston-chamber in the said cylinder and aligned with the gas-passage of the latter; an apertured ring-like sealing-member removably attached to the said cylinder and having a portion extending into the open end of the piston-chamber therein in position to seal the drill-clearance passage in the said cylinder; and a piston reciprocating in the piston-chamber of the said cylinder and having a portion extending outwardly through the said apertured ring-like sealingmember.

5. A gas-operated self-loading rearm-construction including in combination: a barrel having an axial bore; a cylinder adjacent the said barrel and provided with a rearwardly-opening piston-chamber and with a drill-clearance passage in its lower rear portion, the said cylinder also being provided with a forwardly-and-upwardly-inclined gas-passage connecting the forward portion of the piston-chamber in the said cylinder with the bore of the said barrel and having its axis aligned with the drill-clearance passage in the lower rear portion of the said cylinder, the said cylinder being formed in the interior of the rear portion of its said pistonchamber with internal threads; a tubular bushing threaded into the rear end of the pistonchamber of the said cylinder and sealing the drill-clearance passage therein and formed with a forwardly-facing annular sealing-seat; and a piston comprising a head slidable in the pistonchamber of the said cylinder and also comprising a stem extending rearwardly through the said bushing, the saidl piston being provided with an annular rearwardly-facing sealing-surface engageable with the annular sealing-seat of the said bushing at a point forwardly of the drillclearance passage in the said cylinder.

6. A gas-operated self-loading rearm-construction as set forth in claim 5, and in which the annular forwardly-facing sealing-seat of the said bushing is conically contoured and in which the annular rearwardly-facing sealing-surface of the said piston is conically contoured for engagement with the similarly contoured sealing-seat of the said bushing.

'7. A gas-operated self-loading 'firearm including in combination: a barrel provided with a cylinder-lug unitary therewith and having a rearwardly-opening piston-chamber, the said cylinder-lug being provided in its lower rear edge with a clearance-notch extending outwardly from the piston-chamber therein, and the said cylinder-lug also being formed with a forwardly-andupwardly-inclined gas-passage aligned with the notch in the cylinder-lug and extending at its upper portion into communication with the bore of the said barrel; a piston movable in the pistonchamber of the said cylinder-lug under the urge oi gas pressure from the bore of the said barrel; and a tubular stop-member removably installed within the rear end of the piston-chamber in the said cylinder-lug and having a portion overlapping and sealing the inner end of the clearance-notch therein. j

DAVID M. WILLIAMS. 

